Loading stop for electron tube making machines



April 29, 1952 c. w. DALEY 2,595,058

LOADING STOP FOR ELECTRON TUBE MAKING MACHINES Filed Sept. 50, 1949 WZZM (Ittorneg Patented Apr. 29, 1952 LOADING STOP FOR ELECTRON TUBE MAKING MACHINES Charles W. Daley, Indianapolis, Ind, assignor to Radio Corporation of America, a corporation of Delaware Application September 30, 1949, Serial No. 118,328

9 Claims. (01. 49-2) The present invention relates to electron tube makingmachines known as Sealex machines for sealing envelope parts of electron tubes and exhausting the envelope, and more particularly to a loading stop for such machines for accomplishing a' desired orientation of bulbs of electron tubes with respect to parts of the machines.

One type of Sealex machine comprises concentric turrets, one of the turrets serving to seal glass bulbs to glass stems and the other accomplishing the exhaust of the envelop provided by the bulb and stem. This machine is adapted to function in association with a tube mount including a button type of glass stem having leadins extending therethrough, and a bulb having an open end for receiving the mount and an exhaust tubulation in the other end. The machine includes a plurality of heads on which are monuted chucks constituting supports for the mount and having apertures of predetermined depth for receiving the lead-ins extending from the stem.

Prior to mounting a bulb and stem on a chuck, anelectrode assembly mounted on the stem is extended into the bulb with the edge of the stem frictionally engaging the inner wall of the bulb adjacent its open end. The resultant loosely assembled unit is then mounted on a chuck of the Sealex machine by extending the lead-ins projecting from the exterior face of the stem into registering apertures in the chuck. The depth of these apertures is predetermined to provide a shelf on which the ends of the lead-ins rest, resulting in a proper vertical position of a stem on a chuck, and a spacing of the stem from the upper face of the chuck for contributing to a goodseal between the bulb and stem.

It is desirable that the envelope including the bulb and stem conform to a predetermined longitudinal dimension. To this end it is necessary that the bulb be also spaced a predetermined distance from the upper face of the chuck. However, the initial mounting of a stem and bulb on a chuck according to prior practices does not accomplish a critical vertical disposition of the bulb with respect to the chuck. As a consequence prior practices have required an additional operation for securing the desired vertical spacing of the bulb from the chuck. This operation has involved the application by the operator of a downward thrust on the bulb at a later stage when the chuck on which the assembly is mounted moves to another position opposite a pivoted arm having an upper surface against which a portion of the edge of the bulb 2 at its open end is adapted to abut. This additional operation that prior machines require limits the speed of a machine and increases operator fatigue.

Another objection to prior machines is that the pivoted arm heretofore used for spacing the bulb from the chuck has been disposed to be in registry with only one chuck, whichlimits the time during which the spacing operation can be performed. The relative shortening of this time requires a high order of concentration on the part of the operator in order to be certain that a downward thrust on the bulb is applied during the relatively short interval that a chuck is adjacent the arm referred to. This necessary degree of concentration contributes to further fatigue on the part of the operator.

As a further consequence of the relatively short time allowed for the bulb orientation operation by prior machines, frequent failures to properly position a bulb on a chuck were likely to occur, with a resultant rise in shrinkage, even at the relatively slow rates at which prior machines have heretofore been operated. With high machine speeds now contemplated for securing increased output and economy, the disadvantage above referred to would entail prohibitive shrinkage.

Accordingly it is the object of the invention to provide an improved electron tube making machine of the Sealex type adapted for operation at increased speed with reduced operator fatigue.

Another object is to provide a Sealex machine in which assemblies to be worked on are properly mounted in one operation.

A further object is to provide a fixed reference surface on a Sealex machine for determining a proper vertical disposition of a bulb on the machine at the initial mounting of the work assemblies on the machine.

Another object is to provide a loading stop for a Sealex machine having a surface critically spaced from the plane of the upper face of a chuck on the machine for receiving in butt relation an end portion of a bulb mounted on the chuck for critically spacing said bulb from the chuck.

A further object is to provide a loading stop for each other.

creased speed of operation of the machine with reduced fatigue effects on the operator.

According to the invention a loading stop is mounted on fixed supports of a Sealex machine and is provided with an edge having an arcuate contour and an upper surface lying in a horizontal plane. The stop is mounted in such a manner that the plane of the surface referred to is spaced vertically a predetermined distance from the plane of the upper surface of a chuck of the machine and in close proximity to the sides of several chucks. The upper surface of the stop therefore constitutes a reference surface against which an end of a bulb to be sealed to a stem is adapted to abut on mounting a loosely joined stem and bulb on a chuck adjacent the stop.

Further objects and advantages of the invention will manifest themselves as the present description continues.

Referring to the drawing for illustration of anembodiment of the invention,

Figure l is a fragmentary plan view of the upper turret of a Sealex machine including my novel loading stop, said upper turret being adapted to accomplish a seal between the bulb and stem of an electron discharge device;

Figure 2 is a view partly in section along the line 2-2 of Figure l Figure 3 shows a mount and bulb loosely held together at a fire station of the machin for sealing of the stem to the bulb; and

Figure 4 illustrates a prior art expedient for properly positioning and spacing a bulb vertically with respect to a chuck of a Sealex machine.

Referring in more detail to the drawing there is shown in Figure 1 thereof a top view of a portion of the upper turret of a Sealex machine for sealing a bulb to the stem of a tube mount. The machine may include I8 heads fixed to a rotatable support for travel successively through a pinrality of stations including a loading station, annealing stations and a sealing station.

Each head includes a chuck It] mounted on a rotatable support ll. Also mounted on support H for rotation therewith is a structure for holding a bulb in position once it has been properly mounted on the chuck l3. This structure includes a pair of gripper arms l2, l3 for firmly engaging the bulb. The gripper arms are mounted on support I l for rotation in opposite directions as a consequence of which the arms are caused to selectively approach and recede from To synchronize the rotation of the arms on each hand, spur gears l5, [8 are provided which mesh with each other.

The chuck includes an insert [1 as shown in Figures 2 and 3 which is provided with vertically extending apertures l8 for receiving leadins l9 extending from glass button stem 20 and electrode assembly 21. The apertures l8 terminate in a shelf provided by the bottom of the recess in chuck [0 that receives the insert H. The depth of the apertures or holes I8 is predetermined and coordinated with the length of leadins l9 extending from the outer surface of stem 26. The apertures 18 are spaced from each other so as to be in registry with the lead-ins [9. Consequently a placement of the mount on seal to be made between the stem 20 and bulb 22.

The initial loose attachment between the bulb 22 and the stem 20 prior to mounting on the machine is not critical with respect to the longitudinal spacing of the bulb in relation to the stern. However, such critical spacing is required in the finished product. It is not feasible to permit the bulb to rest on the upper surface of chuck III for accomplishing such spacing, since a good seal requires separation of the region of the seal from adjacent members or structures. Therefore, to accomplish the critical spacing referred to prior to the sealing operation, it has been customaryheretofore to resort to a separate positioning operation. Thus, prior mounting practices have involved the operation of placing the loosely joined bulb and mount structure on a chuck with the mount automatically becoming properly oriented vertically by an abutment of the lead-ins thereof on the shelf referred to, but with no provision for properly positioning and spacing the bulb vertically. Since the operation referred to would not accomplish a desirable positioning of the entire bulb stem assembly on a chuck, prior mounting procedures required the additional operation of critically spacing the bulb with respect to the mount. This operation was performed after the turret had been subjected to one or two indexing movements, after the original placement of the assembly on the chuck, so that the position with respect to the operator at which the mount and bulb were initially placed on a chuck was displaced from the position at which the bulb was correctly positioned thereon.

The additional operation required by prior art practices referred to utilized the upper surface of a pivotally mounted arm 23 shown in Figure 4 as a reference surface, the arm being urged against .a side of one chuck indexed into registry therewith. The time during which a chuck is adjacent arm 23 was relatively short, which required relatively close and fatiguing attention of the operator on the work. According to this operation the operator was called upon to press down the bulb so that its lower edge engaged the reference surface on'arm 23 during the relatively short time that arm 23 was disposed adjacent the head supporting the bulb. Consequently, prior machine structures have required mounting procedures that have required relatively rapid and extended movements on the part of the operator and that have not only resulted in relatively high operator fatigue but have limited the speed at which the machine could otherwise operate.

I have found that a modification in the structure of a Sealex machine of the type described permits the operator to place a bulb and mount in the desired position on a chuck in one single operation and at a location of a sealing head in one of several indexing positions. This modification comprises an arcuate loading stop 24 mounted on a fixed support of the machine, such as ring 25, with the upper surface of the stop disposed slightly above the upper surface of chuck it), as shown in Figure 2. The vertical displacement of the upper surface of the loading stop from the end surface of chuck I0 is predetermined to afford displacement of the open end of bulb 22 from the chuck I0 required for eliminating strains in making the seal and for rendering the lengths of several sealed assemblies uniform.

My novel loading stop is disposed in registry with several indexing positions of a head of the machine. In Figure 1 my stop is shown as having a length for engaging three heads simultaneously. This contributes to greater flexibility in the operation of mounting a bulb and mount on a chuck. For example, if the machine is set to perform a predetermined number of indexing movements in a unit of time, one order of speed of mounting permits the operator to complete a mounting operation as soon as a head comes into registry with the stop. This speed may be reduced gradually until the mounting operation is performed when the head is in its intermediate position in registry with the loading stop. This variation in speed that my novel loading stop permits greatly reduces the fatigue incidental to the mounting operation. At the final position of the head in registry with the loading stop, gripper arms I2, 13 are closed around the bulb to hold it in its properly fixed position throughout travel of the head during the sealing cycle.

My novel loading stop is of arcuate shape to permit engagement of its inner edge with several chucks disposed in an are on the rotatable turret. While both edges of my stop are shown as arcuate, the inner edge only is required to be arcuate and the other edges may have any other outline desired.

It will thus be apparent that I have provided a novel and improved electron tube making machine that includes a novel loading stop for rendering the operation of loading the machine less fatiguing on the operator in that fewer operations are required, and increasing the speed at which the machine can be operated without appreciably increasing the burden on the operator.

Various modifications may be made in structure embodying my invention without departing from its spirit and I desire to include such modifications within the scope of the appended claims.

I claim:

1. A machine for sealing electron tube envelope parts comprising a plurality of heads rotatable in a common circular path, a chuck on each of said heads having an upper surface lying in a horizontal plane and adapted to receive lead-ins extending from a loosely held assembly comprising a tube mount and a bulb for orienting said mount with respect to said chuck, and a loading stop extending adjacent a plurality of said heads, said loading stop having an upper surface lying in a horizontal plane and spaced vertically above said upper surface of said chuck for engaging an end of said bulb at any one of a plurality of different positions of said chuck for spacin said bulb a predetermined distance above said sealing pin, whereby a normal loading of said assembly on said chuck in a predetermined sealing position is facilitated.

2. A machine for sealing envelope parts of an electron tube, having a turret for sealing a flat glass stem to an open end of a glass bulb, including a head mounted for indexed rotation through a plurality of stations disposed along the periphery of said turret including a loading station, said head including means for supporting said stem in a predetermined position for sealing, a loading reference means extending along three successive indexed posistions of said head at said loading station, said loading reference means having a horizontal surface extending into the path of travel of said bulb to said stem, whereby said bulb is correctly positioned with respect to said stem in response to a single positioning operation at the first two of said successive indexed positions, and means operative to fix the position of said bulb with respect to said stem while the head on which said bulb is -mounted is in registry with said reference means at the third of said successive indexed positions.

3. A sealing machine having a turret for sealing a glass stem to a glass bulb and including a head mounted for indexed rotation, said head including a chuck for receiving said stem in predetermined spaced relation with respect to said chuck for reducing heat conduction from said stem to said chuck, and a loading stop having a length for registry with said head during several successive indexed positions thereof, said stop having a surface extending into the path of travel of said bulb to said stem for properly positioning said bulb with respect to said stem and spacing said bulb from said chuck, whereby said bulb is properly mounted on said head in one operation during any portion of a relatively long time duration, and means for engaging said bulb for fixing its position with respect to said stem and chuck for accomplishing a good seal, said means becoming operative to fix said bulb with respect to said stem and chuck when said 'head is in registry with a terminal portion of said stop.

4. A glass sealing machine having a turret mounted for indexed rotary movement, a head on said turret movable therewith for receiving a frictionally assembled glass stem having leadins extending therefrom and a glass bulb, a chuck on said head for receiving portions of said lead ins with said stem spaced from said chuck, and a loading stop having a surface extending into the path of travel of said bulb during the mounting of said assembled stem and bulb on said chuck for suitably spacing said bulb from said pin, said stop having a length extending along several successive indexed movements of said head, whereby said assembled stem and bulb are adapted to be manually mounted on said head in a single operation and during a non-critical portion of a relatively long time interval.

5. A machine for sealing two loosely assembled parts to form an electron tube envelope, comprising a plurality of chucks for successively receiving a plurality of said assembled parts, means on said chucks for orienting one of said parts in spaced relation with respect to a chuck, and a loading stop extending adjacent the sides of at least two of said chucks, and having a surface spaced from said chuck for orienting the other of said parts with ,respect to said chuck in a sealing position, whereby a manual loading of said parts on said chucks is facilitated.

6. A machine for sealing together two frictionally assembled parts to form an electron tube envelope, comprising a plurality of spindle chucks mounted for intermittent lineal movement, whereby said chucks are moved successively through a plurality of stations including a manual loading station, means on said chucks for orienting one of said two parts in predetermined sealing position on one of said chucks, and means comprising a loading stop at said loading station for orienting the other of said two parts in a predetermined sealing position, said loading stop extending adjacent a plurality of said chucks, whereby a manual loading of said chucks may be effected in one of a plurality of different positions thereof for facilitating the loading operation.

'7. In a turret type machine for sealing a flat stem including a disc having lead-ins extending therethrough, to an open ended envolope to close said envelope, the combination of a plurality of spindle chucks each having a planar surface and a plurality of apertures in said surface communicating with shelves spaced a predetermined distance from said surface for receiving said lead-ins with said disc spaced from said surface, and a loading stop extending adjacent the sides of a plurality of said chucks and having a surface spaced normally from the planar surfaces of said chucks, said surface of said loading stop extending into the path of movement of said envelope when said envelope is loaded on one of said chucks for spacing said envelope from the planar surface of said one of said chucks, whereby the loading of said envelope on said chuck is facilitated.

8. In a machine for sealing a fiat stem including a disc having lead-ins extending therethrough to an open ended envelope to close said envelope, and including a plurality of spindle chucks having means for receiving stems with the discs thereof in spaced relation from surfaces of said spindles for reducing strains in said stems during a sealing operation, the improvement comprising an elongated loading stop having a surface spaced normally from said surfaces of said chucks and extending into the path of movement of said envelopes during a normal loading thereof on said chucks, for spacing said 8 envelopes from said surfaces in a sealing position, said loading stop extending adjacent a plurality of said chucks for facilitating a manual loading operation.

9. A sealing machine having a plurality of spindle chucks movable intermittently in a predetermined path through a loading and a gripping station and adapted to receive a glass stem frictionally held by an open ended glass bulb, means on said chucks for receiving and orienting one of said stems in a redetermined sealing position, means for orienting one of said bulbs in said predetermined sealing position, and means for gripping said bulbs to fix said orientation thereof, said bulb orienting means comprising a loading stop extending simultaneously adjacent a plurality of said chucks at said loading station and said gripping station, whereby said bulb is gripped while oriented by said loading stop to prevent displacement thereof from said predetermined sealing position.

CHARLES W. DALEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,100,656 Donovan et al Nov. 30, 1937 2,296,579 Seelen Sept. 22, 1942 2,447,568 Eisler Aug. 24, 1948 

